CVE-2026-77802 HTTP Request Smuggling Vulnerability in Progress® Telerik® Fiddler® Classic

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while...

PT-2026-105990

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode...

CVE-2026-77804: Time-of-check Time-of-use (TOCTOU) Race Condition

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, a time-of-check time-of-use TOCTOU race condition exists in the installation of the HTTPS interception root certificate into the Local Computer certificate store. Fiddler writes the certificate to a temporary...

CVE-2026-77803: Inconsistent Interpretation of HTTP Requests

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, front-end request desynchronization is possible in the proxy request forwarding component. A request that contains both a Content-Length and a Transfer-Encoding header is forwarded with both headers present,...

CVE-2026-77802: Inconsistent Interpretation of HTTP Requests

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while...

PT-2026-105988

Name of the Vulnerable Software and Affected Versions Progress Telerik Fiddler Classic for Windows versions prior to 6.0.20262.10021 Description Front-end request desynchronization is possible in the proxy request forwarding component. When a request contains both Content-Length and...

PT-2026-105987

Name of the Vulnerable Software and Affected Versions Progress Telerik Fiddler Classic for Windows versions prior to 6.0.20262.10021 Description HTTP request smuggling is possible in the proxy request forwarding component. This occurs when requests containing multiple Content-Length headers with...

PT-2026-105989

Name of the Vulnerable Software and Affected Versions Progress Telerik Fiddler Classic versions prior to 6.0.20262.10021 Description A time-of-check time-of-use TOCTOU race condition occurs during the installation of the HTTPS interception root certificate into the Local Computer certificate stor...

CVE-2026-77805: Improper Verification of Cryptographic Signature

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode...

Analyzing and remediating a malware infested T95 TV box from Amazon

A couple of weeks ago, security news outlets made their rounds reporting on an Android TV box available on Amazon that came pre-installed with malware. The findings came from a Canadian developer, Daniel Milisic, who posted on his GitHub. What Daniel found was an Android T95 TV box infected with...